... in design,and light in weight.The balls contact with the circular race at four points,via which ... with screw holesC.Outer rings with installation screw holes,inner ring with intallation bolt holesD.Outer ring with intallation bolt holes,inner ring with intallation screw ... ball,bigger module,outer gear,Outer ring with installation screw holes,inner ring with installation bolt holes,Dia.of track center ...